Comparative study of airborne pollen in Shipai area of Guangzhou City from 1986 to 1987 and 2021 to 2022

Airborne pollens are significant allergens for respiratory allergic diseases such as asthma and allergic rhinitis. Over the past few decades, the global rise in temperature and increased levels of atmospheric carbon dioxide have affected the duration and quantity of pollen production. However, there were few studies on the changes in pollen concentration in the Shipai area of Guangzhou over the past few decades. This study monitored the concentration of airborne pollen in Guangzhou’s Tianhe Shipai from November 1, 2021, to October 31, 2022, using a Durham gravity sampler. The analysis showed that a total of 7,310 pollen grains were collected from November 2021 to October 2022, significantly fewer than the 13,080 grains collected 35 years ago. There were 23 days when the daily pollen concentration exceeded 50 grains/1,000 m2, with 1 day in February, 14 days in March, 5 days in April, and 3 days in September. A total of 21 types (families and genera) of pollen were identified in this collection, compared to 41 types (families and genera) identified 35 years ago. This year, more than 500 grains of pollen were collected from the Moraceae, Pinaceae, and Cupressaceae families, while 35 years ago, it was from the Eucalyptus, Bauhinia, Casuarina, Melaleuca, and Poaceae families. The pollen collection showed three peaks this year, compared to only two peaks 35 years ago. The first peak occurred in March with the highest pollen count, similar to 35 years ago. The second peak was in April, whereas it was in May 35 years ago, and the third was in September. In conclusion, there is a significant difference in airborne pollen in the air of the Shipai area of Guangzhou, between 35 years ago and now. Although the concentration and types of pollen are lower than 35 years ago, the pollen peak periods have increased, and the dominant pollen is also different. Thirty-five years ago, it was Eucalyptus, Bauhinia, Casuarina, Melaleuca, and Poaceae, while after 35 years, it was Moraceae, Pinaceae, and Cupressaceae. Therefore, it is important to pay attention to the changes in allergenic pollen in the Guangzhou area and to further study the correlation between allergenic pollen and respiratory allergic diseases, providing an important basis for prevention, treatment, and early warning for patients with pollen-induced allergic diseases in the Guangzhou area.